1. Field of Invention
The present invention relates generally to the field of telecommunications. More specifically, the present invention relates to the field of providing telephone services to telephone subscribers in the context of local number portability.
2. Background of the Invention
Historically, the telephone service infrastructure has been based on the concept that groups of telephone numbers are assigned to a particular switch. These assignments provided predictability in determining where a telephone number was homed, and where information relating to that telephone number could be obtained. Under this system, if a telephone subscriber changed his or her telephone service, requiring a telephone number in an area served by another switch, that telephone subscriber would be issued a new telephone number, which would be homed on the switch servicing the subscriber""s new area. Such changes could occur for a number of reasons including, for example, the telephone subscriber moving from one telephone company to another telephone company. As can be imagined, changing a telephone subscriber""s telephone number caused the telephone subscriber significant inconvenience including, for example, the burden of informing others of the telephone number change.
To avoid this inconvenience, local number portability (LNP) was instituted. LNP is described in Telcordia standard GR-1299-CORE: Switch-Service Control Point (SCP)/Adjunct Interface Generic Requirements, Issue 3, July 1996, which is hereby incorporated by reference herein in its entirety. Briefly, with LNP, a telephone subscriber can keep his or her telephone number despite making changes in telephone service that require his or her telephone number to be homed on a different switch. Moving a telephone number from one switch to another is referred to as porting the telephone number. By allowing telephone numbers to port, however, LNP destroys the original assignment of telephone numbers to particular switches. Consequently, LNP removes the predictability of telephone number-switch assignments that facilitates routing of telephone numbers, and identifying where information about the telephone numbers is located.
To overcome this problem, LNP standard 1299 provides Global Title Translation (GTT) routing. In LNP routing, an LNP routing record is created for each ported telephone number. An LNP routing record includes the telephone number""s call routing and any service routings associated with the telephone number. FIG. 1 illustrates an exemplary LNP routing record 101. LNP routing record 101 contains a telephone number 102 and a local routing number (LRN) 104 corresponding to telephone number 102. LRN 104 is the network address of the switch on which telephone number 102 is homed.
The LNP routing record also contains GTT routings corresponding to certain additional services associated with the telephone number. Such services include Customized Local Area Signaling Services (CLASS), caller ID name identification (CNAM), Inter-Switch Voice Messaging (ISVM) and Line Information Database (LIDB). Each service routing record contains a destination point code (DPC) and a subsystem number (SSN). The DPC is an address of a server on the telephone signaling network that provides the particular service. The subsystem number identifies the particular application executed by the server to implement the service being provided. Exemplary service routings are illustrated as service routings 1-4 in FIG. 1. Using the DPC and SSN, a service request can be issued over the telephone network to provide the service.
When a telephone number is ported, each telephone company having an interest in the porting is advised of the change. FIG. 2 is a schematic illustration of a conventional system 201 for updating LNP databases to reflect a particular telephone number porting. A first telephone company 202 notifies number portability administration center (NPAC) 204 that a telephone number, TN, is porting to it by sending NPAC 204 a notification message 203 advising NPAC 204 of TN""s porting. Service message 203 provides NPAC 204 with a telephone number record 208. Telephone number record 208 is an LNP routing record for telephone number TN. Telephone number record 208 also contains four form fields called capability codes.
When NPAC 204 receives LNP routing record 208, it broadcasts LNP routing record 208 to all telephone companies in the region, for example, telephone companies 206a and 206b. Telephone companies 206a and 206b use the information contained in LNP routing record 208 to update their respective LNP databases.
For example, with respect to a telephone company 206b, NPAC 204 broadcasts service message 203 through LNP gateway 209 to a service management system (SMS) 210. SMS 210 obtains telephone record 208 from service message 203, and stores it in an SMS database 216. From the information contained in the LNP routing record 208, a network element record 218 is created. Network element record 218 is a record containing routing information for the telephone number including a local routing number and service routing (destination point code and subsystem number). In this example, SMS 210 then accesses database 216 to transmit network record element 218 to service control points (SCPs) 212a and 212b. SCPs 212a and 212b store network element record 218 in their respective LNP databases 214a and 214b. 
Services, for example calling name identification (CNAM) service, associated with particular telephone numbers can also be affected by LNP. FIG. 3 illustrates a schematic diagram of a system 301 for providing CNAM service conventionally in the LNP environment. Referring to FIG. 3, when a calling party 302 calls a called party 304, switch 306, on which calling party 302""s telephone number is homed, communicates with switch 308, on which called party 304""s telephone number is homed, across SS7 network 310 to establish the telephone call. Switch 308 is owned by telephone company 330. Telephone company 330 provides CNAM processing for telephone numbers homed on switch 308. Switch 308 determines that called party 304 subscribes to the caller name identification (CNAM) service. The CNAM service is described in Telcordia standard Lata Switching System is Generic Requirements, xe2x80x9cClass Features: Calling Name Delivery Requirements,xe2x80x9d FSD01-02-1070, TR-NTW-001188, Issue 1, December, 1991, which is hereby incorporated by reference herein in its entirety. There are four types of CNAM service depending on where calling party 302""s telephone number is homed and industry agreements.
A first case of CNAM service is for telephone numbers of subscribers of a telephone company that manages its own CNAM databases, for example, telephone company 330. For these subscribers, telephone company 330""s CNAM databases 316a-d contain the telephone number and directory name corresponding to each telephone number for its subscribers.
A second case of CNAM service is for telephone numbers of subscribers whose telephone numbers are homed on a switch owned by another telephone company that does not maintain its own CNAM databases, for example telephone company 332. Generally, telephone company 332 enters into an agreement for telephone company 330 to provide CNAM service for its subscribers. In this case, telephone company 330""s CNAM databases contain the telephone numbers and corresponding directory names for telephone company 332""s subscribers. For the second type of CNAM service, telephone company 332 issues the CNAM query, as described above with respect to the first case of telephone numbers to telephone company 330""s CNAM service.
A third case of CNAM service is for the telephone numbers of subscribers whose telephone numbers are homed on the switch of another telephone company that maintains its own CNAM database, for example telephone company 334. In this case, telephone company 334 enters into an agreement with telephone company 330 to provide CNAM processing for telephone company 334""s subscribers. For the third case of CNAM service, LNP SCP 320 directs the CNAM query to telephone company 334 for processing.
A fourth case of CNAM service is for the telephone numbers of subscribers whose telephone numbers are homed on the switch of a telephone company, for example telephone company 336, for which there is no agreement in place regarding the handling of CNAM service. For the fourth case of CNAM service, telephone company 330 returns a default message in response to the CNAM query. For example, telephone company 330 can return city and state information regarding the calling party number in response to the CNAM query.
In conventional systems, STP 314 routes the CNAM query for processing on the basis of the 6-digit NPA-NXX. As is well-known, the NPA-NXX corresponds to the first six digits of a ten-digit telephone number that can be used for routing purposes. If the NPA-NXX corresponds to a telephone number served by the first or second case of CNAM service, STP 314 directs the CNAM query to CNAM SCP 312a-d. CNAM SCP 312a-d are connected to CNAM databases 316a-d respectively. CNAM databases 316a-d store telephone numbers and their corresponding directory names. When CNAM SCP 312a-d receives the query, it performs a database lookup of CNAM databases 316a-d, using the calling party telephone number as an index, to obtain the calling party name (i.e., directory name) associated with calling party 302""s telephone number. A message containing the calling party name and telephone number is sent to switch 308. Switch 308 transfers the information to a caller ID display device 318 on which calling party 302""s telephone number and calling party 302""s name are displayed to called party 304.
If the NPA-NXX corresponds to a telephone number served by the third case of CNAM service, STP 314 routes the CNAM query to telephone company 334 for processing. Calling party 302""s directory name is returned to switch 308, and is ultimately displayed along with calling party 302""s telephone number on called party 304""s caller ID display device 318.
If the NPA-NXX corresponds to a telephone number served by the fourth type of CNAM service, STP 314 routes the CNAM query to CNAM SCP 312a-d which returns a default message to switch 308 in response to the CNAM query. For example, CNAM SCP 312a-d can return city and state information regarding the calling party number to switch 308 in response to the CNAM query.
A number of problems arise in the conventional system for processing CNAM queries in the LNP environment. For example, when a telephone number is ported out of the first or second cases of CNAM service, the telephone company must diligently remove that telephone number""s information from its databases. If it does not, the telephone company may deliver incorrect CNAM information in response to a CNAM query for that telephone number.
Another problem is CNAM query loops. A CNAM query loop can occur when a telephone number served by the third type of CNAM service is ported to a home switch where it is served by the first or second type of CNAM service, for example a telephone number ported from telephone company 334 to telephone company 330. In this case, STP 314 sends a CNAM query to the telephone company 334 for processing based on the 6-digit NPA-NXX. Telephone company 334 looks in its databases and determines that the subscriber is no longer in its databases. Because it cannot process the CNAM query, telephone company 334 sends the CNAM query back to STP 314 for processing. Upon receipt of the CNAM query, STP 314 processes it by sending it back to the telephone company 334. This results in a CNAM query loop. Manual action may be required by an operator to stop the CNAM query loop.
In a conventional LNP processing system operating at BellSouth Corporation of Atlanta, Ga. (the xe2x80x9cBellSouth systemxe2x80x9d), a calling party initiates a phone call to a called party subscribing to the CNAM service. When the switch on which the called party telephone number is homed receives the calling party""s attempt to make a call to the called party, it issues a CNAM query to a signaling transfer point (STP) to obtain CNAM information corresponding to the calling party. The STP forwards the query to an LNP services control point (SCP) to obtain routing information to handle the CNAM query. The CNAM query is then routed according to the routing information. Generally, the CNAM query is routed to a CNAM SCP. Using the calling party""s telephone number (contained in the CNAM query) as an index into CNAM databases containing telephone numbers and their corresponding directory names, the CNAM SCP obtains the CNAM information required to respond to the request. The response to the CNAM query (directory name and telephone number) is displayed to the called party on a caller ID display device.
In the conventional BellSouth system, STP 314 is modified to send all CNAM queries to LNP SCP 320. This modification can be accomplished by changing the routing tables in STP 314 to send all CNAM queries to LNP SCP 320. In this manner, LNP SCP 320 can access LNP databases 322a-c to determine where the information for answering the CNAM query is located for a particular telephone number. Importantly, under GTT routing, LNP SCP 320 accesses LNP databases 322a-c using the full 10-digit telephone number. This provides the most accurate service routing information available for a particular phone number.
In operation, STP 314 sends the CNAM query to LNP SCP 320. LNP SCP 320 performs a database lookup in databases 322a-c to obtain the LNP routing record corresponding to the telephone number in the CNAM query (calling party 302""s telephone number). Once the LNP routing record is obtained, SCP 320 extracts the DPC and SSN corresponding to the CNAM query. This DPC provides the address of the network element that responds to CNAM queries for the telephone number contained in the CNAM query.
If the information to respond to the CNAM query can be found in a CNAM database owned by telephone company 330, for example, in CNAM databases 316a-d, (i.e., the calling party telephone number is served by the first case or second case of CNAM service). The query is then routed to CNAM SCP 312a-d. CNAM SCP 312a-d accesses the appropriate CNAM database 316a-d, using the telephone number contained in the CNAM query as an index, to obtain the directory name associated with the telephone number in the CNAM query. The directory name and calling party telephone number are returned to switch 308. Switch 308 causes the directory and name and telephone number to be displayed on calling name display device 318.
If the telephone number in the CNAM query is served by the third case of CNAM service, STP 314 redirects the CNAM query to the network node identified by the DPC and subsystem number for processing. The response to the CNAM query is sent back to switch 308 for ultimate display on CNAM data display device 318. If the telephone number in the CNAM query is determined to be of the fourth case, STP 314 routes the query to a CNAM SCP, which returns city and state data to switch 308 in response to the CNAM query.
FIG. 4A is a flow chart 401 for displaying telephone number and directory name information in a conventional LNP routing system such as the BellSouth system described above. In step 402, STP 314 receives a CNAM query. In step 404, STP 314 routes the CNAM query to LNP SCP 320. To perform step 404, the routing tables in STP 314 are modified to route CNAM queries (except those that telephone company 330 cannot process based on the NPA-NXX) to LNP SCP 320. Using the telephone number in the CNAM query as an index, LNP SCP 320 obtains the LNP routing record corresponding to the telephone number in step 406. LNP SCP 320 obtains service routing information for the CNAM service from the LNP routing record in step 408. In step 410, LNP SCP 320 routes the CNAM query to the network element identified by the DPC in the CNAM service routing of the LNP routing record for processing. In step 412, the telephone number and directory name corresponding thereto returned in response to the CNAM query, or city and state information, are displayed to called party 304 on called ID display device 318.
Referring to FIG. 4B, routing step 410 is described in more detail. In step 420, LNP SCP 320 performs a database lookup in databases 322a-c to obtain the LNP routing record corresponding to the telephone number, TN, in the CNAM query. In step 422, LNP SCP 320 determines if the telephone number is served by the first, second or fourth case of CNAM service. If the telephone call is served by the first, second or fourth case of CNAM service, LNP SCP 320 routes the call to CNAM SCP 312 in step 424. In step 426, CNAM SCP 312a-d determines whether the telephone number corresponds to the fourth case of numbers. If it does, CNAM SCP 312a-d returns city and state information to switch 308 in step 434. The city and state information is then displayed on display device 318 in step 435. If the telephone number does not correspond to the fourth case, then in step 426, CNAM SCP 312a-d performs a database lookup in CNAM databases 316a-d to obtain the directory name corresponding to the telephone number in the CNAM query. If no record is found, as determined by step 428, CNAM SCP 312 returns city and state information to switch 308 in step 434. The city and state information is displayed on caller ID display device 318 in step 435. If a record is found, as determined in step 428, CNAM SCP 312 returns telephone number and directory name information to switch 308. The telephone number and directory information is displayed on caller ID device 318 in step 432.
If, in step 436, LNP SCP 320 determines the telephone number in the CNAM query is served by the third case of CNAM service, then, in step 438, it routes the CNAM query to the network element identified in the LNP routing record for processing. That network element returns the telephone number and directory name information to switch 308 for ultimate display on caller ID display device 318. In step 435 the city and state information is displayed on caller ID display device 318.
It can be seen then that while the advent of LNP provides convenience for telephone subscribers, there is a significant increase in network traffic due to sending the CNAM query to LNP SCP 320 to perform an LNP database lookup to acquire the address of the network server that should process CNAM query. With the increasing popularity of the calling party name service, this additional network traffic could deteriorate the operation of the telephone network, and even cause it to fail.
The present invention solves the foregoing problems in the art by duplicating much of the information in LNP databases in new LNP databases that are made accessible to CNAM SCPs. In addition, the STP is reconfigured to send all CNAM queries to the CNAM SCP rather than the LNP SCP as in conventional systems. Because the CNAM SCPs have access to the information in the LNP databases, no network messaging is required to obtain the routing information necessary to satisfy the requested service, in the preferred embodiment, the CNAM service. Rather, the necessary routing information is obtained from the new LNP databases accessed by the CNAM SCP. In practice, the majority of the CNAM queries are handled by the CNAM SCP, that is, of the first, second or fourth classes of service. Thus, network traffic is limited to the relatively few telephone numbers falling in the third class.
The STP routes the CNAM query to the CNAM SCP. The CNAM SCP first determines the appropriate network element to handle the CNAM query. In most cases that network element will be the CNAM SCP. Consequently, there will be no need to send the CNAM query elsewhere for handling. As a result, network traffic is significantly reduced over a conventional system such as the BellSouth system described above, which must transmit the CNAM query to an LNP SCP and then to a CNAM SCP for processing.
Thus, one object of the present invention is to conserve network resources.
Another object of the present invention is to reduce routing related traffic on the SS7 network.
Yet another object of the present invention is to make LNP routing information available to the CNAM SCP most likely to be responsible for obtaining the information required to perform a particular service.
These and other objects of the present invention are described in greater detail in the detailed description of the invention, the appended drawings and the attached claims.